The Lord promised the
Hebrews throughout their history that one day He would bring a
Messiah. This Hebrew messiah would speak the Word of God, and if any
Hebrew would not obey, he would be treated as an unbeliever.

Deuteronomy 18:18-19

18 - I will raise them up a Prophet
from among their brethren, like unto thee, and will put my words in his
mouth; and he shall speak unto them all that I shall command him.
19 - And it shall come to pass, [that] whosoever will not hearken unto
my words which he shall speak in my name, I will require [it] of him.